Tropical cyclones are among the most devastating of all natural disasters. Individual cyclones are capable of causing catastrophic losses of property and life. In the U.S. alone, the damage bill from landfalling hurricanes over the last 50 years (1946-1995) averages $2 billion per year. The major causes of damage associated with landfalling storms are the strong winds, heavy precipitation, and storm surge. In the U.S., most of the damage is attributed to storm surge. However, in this study our interests are in the strong winds and heavy precipitation. The effects of high winds are generally concentrated within a few kilometers of the coast, while heavy rainfall often affects areas hundreds of kilometers from the coast. Earlier studies suggest that the locations and intensity of maximum surface wind speed and rainfall patterns of a landfalling storm are significantly influenced by local terrain features and boundary layer processes.
In this study, the NCAR/PSU MM5 system is used to simulate landfalling hurricane conditions. The model performance is verified with observations and the basic characteristics of hurricane boundary layer winds and temperatures revealed in many earlier studies. The responses of the model boundary layer winds and precipitation to various terrain features and boundary layer physics are diagnosed. An interesting issue is how the convection-induced vertical momentum exchanges impact the surface wind field. The model simulations enable us to investigate the observable and some of the non-observable details and mechanisms important in depicting the surface wind and precipitation distributions as well as their relationship to the damage field. Findings are helpful in addressing the question of whether existing model techniques and observations are capable of providing useful guidance for effective damage assessment and mitigation in coastal regions.